A marine radiocarbon calibration curve for the Norwegian North Atlantic coast, from Bølling to the Early Holocene (14.4–11.0 ka BP)

The 14 C marine reservoir age in the North Atlantic and Norwegian Sea has varied through the late glacial period. Here I present a curve, called Norcoast25, for the calibration of late glacial and Early Holocene marine 14 C ages from the Norwegian coast. I also present a table of ΔR values that could be used for the calibration of 14 C ages with Marine20. The results are based on paired 14 C dates of terrestrial plant fragments and articulated marine shells found in shallow marine deposits on the outer coast of Western Norway. The shells calcified in marine water and the 14 C reservoir ages represent the surface water off the Norwegian coast. The ΔR value relative to Marine20 decreases from + 300 14 C yr at 14.4 cal ka BP to − 100 14 C yr at 14.2 cal ka BP and is constant throughout the Allerød. At the transition to the Younger Dryas (YD) the ΔR value increases, and reaches a maximum in the middle YD of + 80 14 C yr. At the YD/Early Holocene boundary, the ΔR value drops 200 14 C yr. These late glacial ΔR values from Norway’s west coast are 150–300 14 C yr lower than has been reconstructed from 14 C-dated sediment cores from the open ocean. The Norcoast25 calibration curve can be uploaded to the OxCal calibration program. A link to the file (Norcoast25.14c) is provided at the end of the paper.